After graduation Ohmae subsequently worked as a senior design engineer for Hitachi from 1970 to 1972. In 1972 to 1995 he worked for McKinsey & Company for twenty-three years. As senior partner he ran the company's Japan operations for a number of years. He co-founded its strategic management practice, and served companies in a wide spectrum of industries, including industrial and consumer electronics, finance, telecommunications, food and chemicals. In 1995 he ran for Governor of Tokyo, but lost to Yukio Aoshima.

In 1997 he went to the United States, where he was appointed Dean and Professor of UCLA Luskin School of Public Affairs. In 1997 to 1998, he became a Guest professor of Stanford Graduate School of Business, MBA Program.

In 2011, he became a Project director for Team "H2O", and coordinated in preparing the report "What should we learn from the severe accident at the Fukushima Dai-ichi Nuclear Power Plant?" and submitted the same to Goshi Hosono, the Minister of Environment & Minister for the Restoration of Nuclear Accident. In 2012, he became a member of The "Nuclear Reform Monitoring Committee" of Tokyo Electric Power Company (TEPCO).

Ohmae introduced the Japanese management methods to a broad Western audience, a specifically the Toyota practice of just-in-time production. He also outlined the differences between Japanese and Western companies, in particular: